Automatic temperature compensation for sand sampler - which is fitted on mixer for controlling mouldability of foundry sand

摘要

Temp. compensation appts. is used in controlling the formability of granular material, esp. foundry sand in a mixer. A device removes a sample of sand from the mixer and into a vibrating separator fitted with slots and channels, plus photocells controlling addns. to the mixer. A resistance thermometer is fitted in front of or behind the mixer and is connected to a controller contg. an amplifier which alters the vibration according to the difference between the actual temp. (Ta) and a reference value (Tr). The controller contains potentiometers providing Tr and a correction factor, plus a multiplier. The thermometer is pref. fitted between the sampler and the vibrating separator. Water is added to the mixer to produce sand with a desired mouldability. Appts. provides automatic compensation for variations in the temp. of the sand sample.